<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>图片居中实例</title>
    <style>
        
       div{
        display:flex;
        justify-content: center;
        margin-top: 250px;
       }
       
    </style>
</head>
<body>
    <div class="picture">  
    <img src="示例图片.jpg" alt="一张图片"/>
    </div>
</body>
</html>